RIB/FIB Growth Rates


What is the current growth rate of the BGP RIB/FIB? 
Is it exponential? Linear? Something else?
And what are the drivers?
Is it more specifics/multihoming, or something else?

Are there observable problems related to table size?
e.g. not enough RP or LC memory? 

If so, what tools are available?

Related: Is AS 'meshiness" growing?
How about AS number burn rate?