a simple browserslist config, see http://browserl.ist to check actual coverage (.join(', ') the array to obtain parsable string), see https://github.com/browserslist/browserslist#custom-usage-data for custom usage stats

browserslist.json

{
  "browserslist": [
        ">= 0.25% in my stats",
        ">= 0.5% in CO",
        ">= 0.5% in FR",
        ">= 0.5% in US",
        ">= 1% in alt-SA",
        ">= 2%",
        "last 2 major versions",
        "last 2 years",
        "last 3 chromeandroid major versions",
        "last 3 ios major versions",
        "last 4 safari major versions",
        "ie >= 9",
        "not ie < 9"
    ]
}