There is no "normal", despite all the nonsense you read on Answers.
The systolic pressure (the top number) for a healthy 70-yr old male ranges -on average-, between about 150 and 180 depending on the time of day - the figures for females are slightly less.
The diastolic pressure usually is between about 90 to 100 roughly, but a lot depends on your medical history obviously.
If your pressures are roughly these then you haven't got "high blood pressure" in spite of what you are told.
If your pressures are significantly LOWER than these then it is an indication that the efficiency of your heart's action may be beginning to be impaired.