By Dennis Crouch
These charts are based upon an analysis of all 4.7 million patents issued between January 1976 and January 2014. I basically tallied the number of independent claims in each patent and grouped those according to the patent issue date. Throughout this time, patents have only issued on Tuesdays each week.
The first chart shows the average number of independent patent claims issued each week. Readers will notice a fairly steady rise in claim-count until around 2004 and a significant drop following that. The second chart uses this same data but adds a finer analysis. The second chart shows the proportion of patents having a given number of independent claims. This chart shows the steady rise in claim-count from the 1970s through 2004 is largely explained by a shift away from patents having only one single claim and toward patents with more than three claims. Since 2004, the tide has changed. There are now many fewer patents with more than three claims and a substantial increase in the number of patents with exactly three independent claims.