 By the year 2000.
( ( By ( the ( year 2000 ) ) ) . )
(ROOT (FRAG (PP (IN By) (NP (DT the) (NN year) (CD 2000))) (. .)))
By the 21st century.
( ( By ( the ( 21st century ) ) ) . )
(ROOT (FRAG (PP (IN By) (NP (DT the) (JJ 21st) (NN century))) (. .)))