  We decompose the monthly cosmic-ray data, using several neutron monitor count
rates, of Cycles 19-24 with principal component analysis (PCA). We show using
different cycle limits that the first and second PC of cosmic-ray (CR) data
explain 77-79% and 13-15% of the total variation of the Oulu CR Cycles 20-24
(C20- C24), 73-77% and 13-17% of the variation of Hermanus C20-C24, and 74-78%
and 17-21% of the Climax C19-C22, respectively. The PC1 time series of the CR
Cycles 19-24 has only one peak in its power spectrum at the period 10.95 years,
which is the average solar cycle period for the interval SC19-SC24. The PC2
time series of the same cycles has a clear peak at period 21.90 (Hale cycle)
and another peak at 1/3 of that period with no peak at the solar cycle period.
We show that the PC2 of the CR is essential in explaining the differences in
the intensities of the even and odd cycles of the CR. The odd cycles have
positive phase in the first half and negative phase in the second half of their
PC2. This leads to slow decrease of the intensity in the beginning of the cycle
and at minimum for the odd cycles. On the contrary, for the even cycles the
phases are vice versa and this leads to faster decrease and more rapid recovery
in the CR intensity of the cycle. As a consequence the even cycles have more
peak-like structure. The only exceptions of this rule are Cycles 23 and 24 such
the former has almost zero line PC2, and the latter has similar PC2 than the
earlier odd cycles. These results are confirmed with skewness-kurtosis (S-K)
analysis. Furthermore, S-K shows that other even and odd cycles, except Cycle
21, are on the regression line with correlation coefficient 0.85. The Cycles 21
of all calculated eight stations are compactly located in the S -K coordinate
system and have smaller skewnesses and higher kurtoses than the odd Cycles 23.
