Ray Merrill summarizes Church growth rates since 1830, compares with world population rates.
Ray M. Merrill, Arielle A. Sloan, and Brittanie A. Steele, “Growth of The Church of Jesus Christ of Latter-day Saints in a Global Context,” Religious Educator: Perspectives on the Restored Gospel 16, no. 1 (2015):116-127
As can be seen, the world’s population grew from 1.2 billion in 1830 to 7.2 billion in 2014 and is projected to reach almost 9.4 billion in 2050. The Church’s population grew from 0 in 1830 to 15.3 million in 2014 and is projected to reach 31.3 million by 2050.
During its first ten years, the Church grew by 67 percent annually (fig. 2). During the 1840s, that rate dropped to 12 percent, and for each decade thereafter through the 1940s, it averaged between 2 percent and 4 percent. From the 1950s to the 1980s, the average annual growth rate was near 5 percent. However, since 2000, the average annual growth rate has remained near 2 percent. For each decade since 1830, the average annual growth rate of the Church has exceeded the earth’s average annual population growth rate. The world population growth rate has been fairly constant since the early 1800s at around 2 percent. The current growth rate is now closer to 1 percent.