In current or open accounts there shall not be collected more than fifteen percent interest annually thereon, thirty days after the delivery of the last article or service; provided that the parties may set a higher rate by agreement. History: Laws 1882, ch. 25, § 2; C.L. 1884, § 1736; C.L. 1897, § 2552; Code 1915, § 3527; C.S. 1929, § 89-105; 1941 Comp., § 53-605; 1953 Comp., § 50-6-5; Laws 1977, ch. 293, § 2; 1980, ch. 68, § 3; 1981, ch. 194, § 1; 1983, ch. 254, § 3.