With the maturation of oil and gas production operations in a province or country, fields found by new-field wildcats diminish in size. The actual economic size cutoff is a function of such factors as depth, water depth offshore, and accessibility to transportation infrastructure. Because of the constraint of resource availability, price is now the principal force driving drilling activity. The proportion of new-field wildcats to other exploratory wells has fallen in recent years, but success in new-field wildcats has risen to about 20%. However, only very small fields, less than 1 million BOE, are being found in large numbers. The 200 largest companies, based on lease revenues, drill 30% of all wells and 44% of the footage, and they make 83% of drilling expenditures. The 20 largest companies alone find 60% of the large fields and 20% of the small ones. Through 1979, almost 93% of known gas fields and 94.5% of known oil fields were small, yet they contain only 14.5% of the ultimately recoverable gas and 12.5% of the oil. However, small fields are less capital intensive than equivalent-capacity synthetic-fuel plants, they are extremely numerous, and they are relatively easy and inexpensive to find and put on production.