Here is the main graph that illustrates how parts count has changed over time. You can see that there were two big spikes, there was a decrease and during the rest of the time part count has changed slightly (or not at all).

515561 new parts numbers were added during my observation period. You can see the list of manufacturers that got the most substantial updates below. I was not surprised to see Vishay on the top of the list and I was not surprised that it took almost 60 percent of the total change.

Manufacturer	Change	%
Vishay	300838	58.4%
Susumu	32546	6.3%
Stackpole Electronics	30999	6.0%
API Delevan	25272	4.9%
Microchip	19208	3.7%
CTS	17448	3.4%
TDK	13702	2.7%
ST Microelectronics	11021	2.1%
Bourns	8439	1.6%
Abracon	7166	1.4%
Total	466639	90.5%

I have made some other conclusions as well, but I will not report them at this point in time. I hope someone will find my observations interesting and useful.