Fixes #960 - better explanation of efficiency.

History.md

@@ -6,6 +6,11 @@
 * Fixed issue [#895](https://github.com/jakubpawlowicz/clean-css/issues/895) - ignoring specific styles.
 * Fixed issue [#947](https://github.com/jakubpawlowicz/clean-css/issues/947) - selector based filtering.
 
+[4.1.8 / 2017-xx-xx](https://github.com/jakubpawlowicz/clean-css/compare/v4.1.7...4.1)
+==================
+
+* Fixed issue [#960](https://github.com/jakubpawlowicz/clean-css/issues/960) - better explanation of `efficiency` stat.
+
 [4.1.7 / 2017-07-14](https://github.com/jakubpawlowicz/clean-css/compare/v4.1.6...v4.1.7)
 ==================
 

README.md

@@ -448,7 +448,7 @@ console.log(output.warnings); // a list of warnings raised
 console.log(output.stats.originalSize); // original content size after import inlining
 console.log(output.stats.minifiedSize); // optimized content size
 console.log(output.stats.timeSpent); // time spent on optimizations in milliseconds
-console.log(output.stats.efficiency); // a ratio of output size to input size (e.g. 25% if content was reduced from 100 bytes to 75 bytes)
+console.log(output.stats.efficiency); // `(originalSize - minifiedSize) / originalSize`, e.g. 0.25 if size is reduced from 100 bytes to 75 bytes
 ```
 
 The `minify` method also accepts an input source map, e.g.