Minor segments of the economy also supported slavery and used slaves as artisans, domestic servants, and navigational aides. By the end of the 1700s, the high price of slaves along with increasing antislavery sentiment in the colony caused many to view the system as anachronistic; nonetheless, it was not abolished until after independence was achieved. Colombia's contemporary economy, based on coffee and other agricultural exports, did not emerge until after independence in 1819, when local entrepreneurs were free to capitalize on world markets other than Spain. Although colonialism fostered minimal domestic economic growth, small entrepreneurial efforts began to take shape, so that by the nineteenth century well-defined economic enterprises existed. The economy at that time was based primarily on mining, agriculture, and cattle raising, with contributions also by local artisans and merchants. Socioeconomic changes proceeded slowly; the economic system functioned as a loosely related group of regional producers rather than as a national entity. Land and wealth were still the privileges of a minority. Forced labor continued in the mines, and various labor arrangements existed on the "haciendas", such as sharecropping and low-wage labor. In each case, those owning the land benefited and those working the land remained impoverished. In the late nineteenth century, tobacco and coffee export industries developed, greatly enlarging the merchant class and leading to  population expansion and the growth of cities. The concentration of economic activity in agriculture and commerce, two sectors that focused on opening channels to world markets, continued slowly but steadily throughout the nineteenth century. Following the War of the Thousand Days (1899–1902), Colombia experienced a coffee boom that catapulted the country into the modern period, bringing the attendant benefits of transportation, particularly railroads, communications infrastructure, and the first major attempts at manufacturing. The period 1905–15 has been described as the most significant growth phase in Colombian history, characterized by an expansion of exports and government revenues, as well as an overall rise in the GDP. Coffee contributed most to trade, growing from only 8 percent of total exports at the beginning of the 1870s to nearly 75 percent by the mid-1920s. Beyond its direct economic impact, the expansion of coffee production also had a profound social effect. In sharp contrast to mining and to some agricultural products such as bananas, which were grown on large plantations, coffee production in Colombia historically developed on very small plots of land. As a result, it generated an important class of small landowners whose income depended on a major export commodity. Unprecedented amounts of foreign capital found their way into both private investment and public works during this period because of the strong performance of coffee and other exports.