Table 2 Measures of secular change in USA-strike to basin-wide frequency, and in ratio of MH to HU frequency.

	Time-dependence of the probability parameter (µ) in the Binomial regression (1/century)
	1851–2019	1878–2019	1900–2019	1980–2019
USA hurricane Strikes vs. HURDAT2 basin-wide hurricanes	−0.541 (p < 0.001)***	−0.774 (p < 0.001)***	−1.02 (p < 0.001) ***	−0.602 (p = 0.65)
USA major hurricane strikes vs. HURDAT2 basin-wide major hurricanes	−0.934 (p < 0.001)***	−1.01 (p = 0.0021)***	−1.95 (p = 0.006) ***	−4.151 (p = 0.081)*
USA hurricane strikes vs. Adj. basin-wide hurricanes	−0.0677 (p = 0.62)	−0.316 (p = 0.071)*	−0.533 (p = 0.028) **	N/A
USA major hurricane strikes vs. Adj. basin-wide major hurricanes	−0.116 (p = 0.64)	−0.246 (p = 0.42)	−0.282 (p = 0.47)	N/A
USA major hurricane strikes vs. USA hurricane strikes	0.376 (p = 0.16)	0.266 (p = 0.41)	0.122 (p = 0.78)	−2.43 (p = 0.33)
HURDAT2 basin-wide major hurricanes vs. basin-wide hurricanes	0.677 (p < 0.001)***	0.497 (p = 0.0052)***	0.360 (p = 0.13)	1.70 (p = 0.14)
Adj. basin-wide major hurricanes vs. basin-wide hurricanes	0.424 (p < 0.001)***	0.193 (p = 0.22)	−0.153 (p = 0.47)	N/A

Values are the time-dependent parameter for the probability estimated from a Binomial regression (see “Methods”). First four rows show trends in the fraction of basin-wide frequency striking the United States of America (USA) over four different time periods, last three rows show trends in the fraction of hurricane (HU) frequency that are major hurricanes (MH) over four different time periods, based on a Binomial regression for MH frequency as a subset of HU frequency with time as a covariate (see “Methods”). Counts are based on data from version 2 of the North Atlantic Hurricane Database (HURDAT2, ref. ³³) and the adjustment developed in this study. Values with a p-value less than 0.1 are highlighted by a single asterisk (*), with a p-value less than 0.05 by a double asterisk (**), and less than 0.01 by a triple asterisk (***). Time periods shown as in Table 1.

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