diff --git a/Changelog.md b/Changelog.md
index f72ed22..62dd656 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -13,9 +13,15 @@ npm install --save terrain50-cli
 
 -----
 
+## v1.5
+ - Update dependencies
+ - Add new `analyse-frequencies` subcommand
+
+
 ## v1.4.1
  - `validate` subcommand in `stream` mode: Write aggregated stats when validation is complete
 
+
 ## v1.4
  - [BREAKING] Add new `--use-regex` flag to `validate` subcommand (only takes effect in stream mode: `--mode stream`)
 
diff --git a/package-lock.json b/package-lock.json
index 7ec79ae..f6e1587 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -338,9 +338,9 @@
 			}
 		},
 		"terrain50": {
-			"version": "1.8.0",
-			"resolved": "https://registry.npmjs.org/terrain50/-/terrain50-1.8.0.tgz",
-			"integrity": "sha512-G6wJw0ysZMet0KCqOZr9Cr0OWTjXn00BpZy0SVMfgIE/GiDTeFbCt2EeHANBwKwc93ItLxGua4nWI+5v42jHmw==",
+			"version": "1.8.1",
+			"resolved": "https://registry.npmjs.org/terrain50/-/terrain50-1.8.1.tgz",
+			"integrity": "sha512-bPAOCOcDHgHoLf2Y7uvk09kDZBRKSkIjBNH5kLzufjzaimxaWVJiALegO9RYw5sHRlU+nzbPZ/0trdJjSs/CRQ==",
 			"requires": {
 				"nexline": "^1.2.1",
 				"nnng": "^1.0.0"
diff --git a/package.json b/package.json
index 6e10c74..ea69a63 100644
--- a/package.json
+++ b/package.json
@@ -37,7 +37,7 @@
 		"chroma-js": "^2.1.0",
 		"image-encode": "^1.3.0",
 		"nexline": "^1.2.1",
-		"terrain50": "^1.8.0"
+		"terrain50": "^1.8.1"
 	},
 	"bin": {
 		"terrain50": "./src/index.mjs"
diff --git a/src/Helpers/StreamHelpers.mjs b/src/Helpers/StreamHelpers.mjs
new file mode 100644
index 0000000..aa63cac
--- /dev/null
+++ b/src/Helpers/StreamHelpers.mjs
@@ -0,0 +1,50 @@
+"use strict";
+
+/**
+ * Writes data to a stream, automatically waiting for the drain event if asked.
+ * See also write_safe.
+ * @param	{stream.Writable}			stream_out	The writable stream to write to.
+ * @param	{string|Buffer|Uint8Array}	data		The data to write.
+ * @return	{Promise}	A promise that resolves when writing is complete.
+ * @private
+ */
+function write_safe(stream_out, data) {
+	return new Promise(function (resolve, reject) {
+		// Handle errors
+		let handler_error = (error) => {
+			stream_out.off("error", handler_error);
+			reject(error);
+		};
+		stream_out.on("error", handler_error);
+		
+		if(typeof data == "string" ? stream_out.write(data, "utf-8") : stream_out.write(data)) {
+			// We're good to go
+			stream_out.off("error", handler_error);
+			resolve();
+		}
+		else {
+			// We need to wait for the drain event before continuing
+			stream_out.once("drain", () => {
+				stream_out.off("error", handler_error);
+				resolve();
+			});
+		}
+	});
+}
+
+/**
+ * Waits for the given stream to end and finish writing data.
+ * NOTE: This function is not tested and guaranteed yet. (ref #10 the HydroIndexWriter bug)
+ * @param  {stream.Writable} stream            The stream to end.
+ * @param  {Buffer|string} [chunk=undefined] Optional. A chunk to write when calling .end().
+ * @return {Promise}                   A Promise that resolves when writing is complete.
+ * @private
+ */
+function end_safe(stream, chunk = undefined) {
+	return new Promise((resolve, _reject) => {
+		if(typeof chunk == "undefined") stream.end(resolve);
+		else stream.end(chunk, resolve);
+	});
+}
+
+export { write_safe, end_safe };
diff --git a/src/Subcommands/analyse-frequencies/index.mjs b/src/Subcommands/analyse-frequencies/index.mjs
new file mode 100644
index 0000000..a0d7d02
--- /dev/null
+++ b/src/Subcommands/analyse-frequencies/index.mjs
@@ -0,0 +1,50 @@
+"use strict";
+
+import fs from 'fs';
+
+import Terrain50 from 'terrain50';
+
+import a from '../../Helpers/Ansi.mjs';
+import l from '../../Helpers/Log.mjs';
+
+import { percentage } from '../../Helpers/MathsHelpers.mjs';
+import { write_safe, end_safe } from '../../Helpers/StreamHelpers.mjs';
+
+export default async function(settings) {
+	// 1: Parse settings
+	let stream_in = process.stdin;
+	if(settings.cli.input !== "-") {
+		l.log(`Reading from ${a.hicol}${settings.cli.input}${a.reset}`);
+		stream_in = fs.createReadStream(settings.cli.input);
+	}
+	else
+		l.log(`Reading from stdin`);
+	
+	let stream_out = process.stdout; 
+	if(settings.cli.output !== "-") {
+		l.log(`Writing to ${a.hicol}${settings.cli.output}${a.reset}`);
+		stream_out = fs.createWriteStream(settings.cli.output);
+	}
+	else
+		l.log(`Writing to stdout`);
+	
+	// ------------------------------------------------------------------------
+	
+	let result_map = await Terrain50.AnalyseFrequencies(
+		Terrain50.ParseStream(stream_in),
+		settings.cli.ignore_nodata
+	);
+	
+	let result_arr = [];
+	for(const [ key, value ] of result_map) {
+		result_arr.push([ key, value ]);
+	}
+	result_arr.sort((a, b) => a[0] - b[0]);
+	
+	for(const [ key, value ] of result_arr) {
+		await write_safe(stream_out, `${key}	${value}\n`);
+	}
+	await end_safe(stream_out);
+	
+	stream_in.destroy();
+}
diff --git a/src/Subcommands/analyse-frequencies/meta.toml b/src/Subcommands/analyse-frequencies/meta.toml
new file mode 100644
index 0000000..02dcbee
--- /dev/null
+++ b/src/Subcommands/analyse-frequencies/meta.toml
@@ -0,0 +1,19 @@
+description = "Count the frequencies of data values. Data values are rounded down before counting."
+
+[[arguments]]
+name = "input"
+description = "The input file to analyse (default: stdin)"
+default_value = "-"
+type = "string"
+
+[[arguments]]
+name = "output"
+description = "The output file to write the results to as tab-separated-values (default: stdout)"
+default_value = "-"
+type = "string"
+
+[[arguments]]
+name = "ignore-nodata"
+description = "Ignore NODATA values when analysing."
+default_value = false
+type = "boolean"