README.md in csl-1.5.0 vs README.md in csl-1.5.1

- old
+ new

@@ -137,10 +137,10 @@
 Thanks to Google and the Berkman Center at Harvard University for supporting
 this project as part of [Google Summer of Code](https://developers.google.com/open-source/soc/).
 
 Copyright
 ---------
-Copyright 2009-2015 Sylvester Keil. All rights reserved.
+Copyright 2009-2020 Sylvester Keil. All rights reserved.
 
 Copyright 2012 President and Fellows of Harvard College.
 
 License
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