But usage rate is growing fast - 8.5% per year according to this: https://www.businesswire.com/news/home/20160201005634/en/Global-Helium-Market-2016-2020---Mar

But usage rate is growing fast - 8.5% per year according to this: https://www.businesswire.com/news/home/20160201005634/en/Global-Helium-Market-2016-2020---Market-Grow https://www.businesswire.com/news/home/20160201005634/en/Glo... an (obviously naive) extrapolation at that rate gives 35 years supply.