Good overview 

Time line summary 

NICE guidance  and here 

current UK prescribing  study

US veterans study 

WHO essential medicines

http://www.who.int/medicines/publications/essentialmedicines/20th_EML2017.pdf?ua=1
surgery for peptic ulcers massively reduced – probably at least in part due to PPIs
https://www.ncbi.nlm.nih.gov/pubmed/15460842

JAMA mortality study