Storage size of the blockchain
The storage size of the bitcoin blockchain is increasing with every additional block, at a rate of:
(size of the last block) / (time to mine the last block)
Since blocks are mined about every 10 minutes, and most new blocks are almost at the 1 MB blocksize limit, this rate has become about
1 MB/10 min = 6 MB/hr = 144 MB/day
This is about + 4GB/month and + 52GB per year.