“when did I learn each programming language I know, and how many lines of code have I written in each?”
There are a lot of computer programming languages out there. There are so many that it is unlikely for a single developer to have come across them all, let alone be fluent in each. That being said, the more [computer] languages one knows the better, because they teach different approaches to common problems. For instance, Scheme has no “for” loop, and no “while” loop because of its adherence to pure functions. For some Java programmers that will seem impossible to get around, until in this case the notion of recursion comes to the rescue.
I believe I have had a relatively conventional sampling of languages. The earliest experience I have with programming is with QBasic on DOS. That…may be a little far back to consider a language I know, but the ones in the table below are decidedly more recent 
Please note that the line counts are as of June 2010.
| Language | Est. Lines (2010) | New Est. Lines (2011) | Year Begun |
|---|---|---|---|
| Assembly | 600 – 700 | 2008 | |
| C | 1,200 – 1,500 | 2008 | |
| C++ | 1,200 – 1,500 | 2005 | |
| Java | > 10,000 | > 15,000 | 2007 |
| JavaScript | 300 – 600 | 2005 | |
| Logo | 5,500 – 6,000 | 2003 | |
| PHP | > 10,000 | > 15,000 | 2005 |
| Python | 400 – 800 | > 15,000 | 2010 |
| Scheme | 250 – 500 | 2009 | |
| VB 6 | 300 – 800 | 2004 | |
| VB .NET | 500 – 800 | 2005 |
UPDATE (July 16, 2011): Added new column for current line counts.