You can see the monthly growth rate of the monero blockchain since April 2014 on localmonero.co's "Blockchain Growth" section
+---------+----------+
| Month | Size (M) |
+---------+----------+
| 2014-04 | 15.25 |
| 2014-05 | 174.85 |
| 2014-06 | 599.83 |
| 2014-07 | 802.46 |
| 2014-08 | 1030.13 |
| 2014-09 | 1185.65 |
| 2014-10 | 1287.76 |
| 2014-11 | 1371.53 |
| 2014-12 | 1474.86 |
| 2015-01 | 1549.62 |
| 2015-02 | 1621.59 |
| 2015-03 | 1722.08 |
| 2015-04 | 1791.62 |
| 2015-05 | 1857.20 |
| 2015-06 | 1922.23 |
| 2015-07 | 1988.19 |
| 2015-08 | 2055.28 |
| 2015-09 | 2117.14 |
| 2015-10 | 2184.96 |
| 2015-11 | 2240.43 |
| 2015-12 | 2305.43 |
| 2016-01 | 2382.80 |
| 2016-02 | 2452.68 |
| 2016-03 | 2584.14 |
| 2016-04 | 2691.73 |
| 2016-05 | 2770.36 |
| 2016-06 | 2858.08 |
| 2016-07 | 2942.75 |
| 2016-08 | 3079.65 |
| 2016-09 | 3249.86 |
| 2016-10 | 3423.38 |
| 2016-11 | 3572.91 |
| 2016-12 | 3759.68 |
| 2017-01 | 4473.84 |
| 2017-02 | 5504.82 |
| 2017-03 | 6883.35 |
| 2017-04 | 8222.76 |
| 2017-05 | 10269.73 |
| 2017-06 | 12453.46 |
| 2017-07 | 14553.01 |
| 2017-08 | 18365.08 |
| 2017-09 | 20705.24 |
| 2017-10 | 22732.19 |
| 2017-11 | 25274.80 |
| 2017-12 | 28572.24 |
| 2018-01 | 31273.01 |
| 2018-02 | 32970.93 |
| 2018-03 | 34762.09 |
| 2018-04 | 37324.06 |
| 2018-05 | 40179.29 |
| 2018-06 | 42451.55 |
| 2018-07 | 44596.92 |
| 2018-08 | 46625.33 |
| 2018-09 | 48798.78 |
| 2018-10 | 50066.50 |
| 2018-11 | 50688.78 |
| 2018-12 | 51089.53 |
| 2019-01 | 51439.34 |
| 2019-02 | 51709.25 |
| 2019-03 | 52036.94 |
| 2019-04 | 52518.32 |
| 2019-05 | 53389.03 |
| 2019-06 | 54096.73 |
| 2019-07 | 54637.57 |
| 2019-08 | 55211.77 |
| 2019-09 | 55709.73 |
| 2019-10 | 56204.44 |
| 2019-11 | 56778.70 |
| 2019-12 | 57363.47 |
| 2020-01 | 58104.83 |
| 2020-02 | 58741.28 |
| 2020-03 | 59560.46 |
| 2020-04 | 60578.93 |
| 2020-05 | 61684.86 |
| 2020-06 | 62642.85 |
| 2020-07 | 63608.86 |
| 2020-08 | 64714.19 |
| 2020-09 | 65846.84 |
| 2020-10 | 67121.53 |
| 2020-11 | 68294.29 |
| 2020-12 | 69519.75 |
| 2021-01 | 70789.75 |
| 2021-02 | 71886.93 |
| 2021-03 | 73450.93 |
| 2021-04 | 75049.82 |
| 2021-05 | 76565.44 |
| 2021-06 | 77686.56 |
| 2021-07 | 79134.11 |
| 2021-08 | 80871.90 |
| 2021-09 | 82315.42 |
| 2021-10 | 83983.59 |
| 2021-11 | 85858.07 |
| 2021-12 | 87430.51 |
| 2022-01 | 88939.65 |
| 2022-02 | 90230.76 |
| 2022-03 | 91688.47 |
| 2022-04 | 91905.24 |
+---------+----------+
So as of this month, the blockchain size is 91905.24 / 1024 = 89.751210938 GB
source: https://localmonero.co/blocks/stats/blockchain-growth