Page Optimization

I'm always adding new content to the web site [Engineering Buses], either by inserting additional content to existing pages or just by adding new pages. So far this year 10 new pages have been added to the site, I don't track content enhancement. However I can tell how many pages have been updated, either from SEO practices or content additions, from the modified date on the PC I can tell how many pages have changed..
Jan; 327 page updates.
Dec; 328 page updates.
Nov; 389 page updates.
Oct; 296 page updates.
And so on, like I said I can't tell why a page was updated. However I could say that a page either received an embedded enhancement to help the search engines or had additional content added, and maybe an SEO change. Normally when I fix a page for optimization reasons it just means I added 'alt' or 'title' tags to links or gif files already present on the page.

I also add graphic or pic files all the time. Currently my PC indicates over 1,600 pic file [in a few different formats, gif, jpg..], however some may not be used but still reside on my PC. Maybe 1,500 different pic files and over 1,851 html files ~ both growing all the time.

So this month will have the highest number of visitors ever, not even counting today [numbers aren't in yet]. Here are the best 5 months [Number of Visits];
Jan 2010: 234,085
Oct 2009: 223,689
Nov 2009: 223,327
Mar 2009: 220,620
Jan 2008: 217,694
Graphic; Google Crawl Stats, last three months. At an average of 519 pages crawled a day, you would think that Google would find the 300 odd pages that are up-dated each month.