Table 2. Global slopes (S(G) for all regions) and periodic slopes (S(P_r) for every region).

Region	Year of First WR	Slope Global	Slopes by periods
		1897–2008	1918–1949	1950–1989		1990–2008
Global	1897	0.0101	0.0075	0.0156		0.0094
North America	1897	0.0029	0.0021	0.0046		0.0015
Western Europe	1901	0.0023	0.0040	0.0018		0.0022
Russia	1917	0.0025	0.0006	0.0038		0.0008
				1950–1969	1970–1989
Eastern Europe	1946	0.0026	0.0003	0.0016	0.0045	0.0003
China	1956	0.0007		0.0002		0.0020
Oceania	1910	0.0006	0.0001	0.0008		0.0011
Africa	1928	0.0002	0.0002	0.0002		0.0007

p<0.001 for all results except Eastern Europe 1918–1949 (p = 0.087).