Year Observations     Objects
1858            3          3 
1889            1          1 
1901            1          1 
1920            6          2 
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           14          7 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          228         81 
1991          867        310 
1992          719        292 
1993         1273        474 
1994         1628        599 
1995         2854        999 
1996         2868       1015 
1997         2873        981 
1998        24600      10341 
1999        13449       5130 
2000        37740      15566 
2001        43274      17033 
2002        40477      16974 
2003        60238      24618 
2004        46949      17914 
2005       312182     140213 
2006       338330     150718 
2007       198230      61257 
2008       115885      33113 
2009        97251      27259 
2010       147549      39299 
2011       156734      42803 
2012       184845      40930 
2013       243143      61735 
2014       547669     134443 
2015       792074     205565 
2016       626460     161641 
2017       542277     147194 
2018       330291      92898 
2019       841353     205581 
2020       574768     145636 
2021       785848     185388 
2022       596682     170840 
2023       539975     154503 
2024       591830     170070 
2025       615023     175668 
2026         1152        335