operational: icmp echo out of control?

[Mark Kent <mark () noc mainstreet net>]

Hello,

I've observed that our border routers are getting pinged a fair bit.
I measured on one router and saw:

  5 per second, seems consistent throughout the day,
  roughly 40 different sources every 15 seconds

I took a look at the varied sources and discovered that the sites
are well connected and those that resolve resolve to akamai names.

This isn't more than a nuisance for me, but I run a small net.  
Should I conclude that an ISP with a population 10 times bigger
would have their border routers getting pinged at 10 times the
rate I see?  If so, should we care, or just ignore it?

Thanks,
-mark