Add version penetration level stats

cmd/ursrv/main.go

@@ -1330,6 +1330,7 @@ func getReport(db *sql.DB) map[string]interface{} {
 	r["versionNodes"] = reports
 	r["categories"] = categories
 	r["versions"] = group(byVersion, analyticsFor(versions, 2000), 5)
+	r["versionPenetrations"] = penetrationLevels(analyticsFor(versions, 2000), []float64{50, 75, 90, 95})
 	r["platforms"] = group(byPlatform, analyticsFor(platforms, 2000), 5)
 	r["compilers"] = group(byCompiler, analyticsFor(compilers, 2000), 3)
 	r["builders"] = analyticsFor(builders, 12)