Complex sentence: By the spring of 1937, economic indicators had regained the production, profits, and wage levels of 1929, except for unemployment, which remained high, although it was considerably lower than the 25% unemployment rate seen in 1933.
Split into simpler sentences: By the spring of 1937, production, profits, and wages had regained their 1929 levels. Unemployment remained high, but it was considerably lower than the 25% rate seen in 1933.